Imaging is a key to progress in stem cell research
An important aspect of
stem cell research is the function of the cells that support them and enable them
to function properly. These systems of supportive cells — called niches —
sequester stem cells from apoptotic and differentiation stimuli and prevent excessive
stem cell production, which could lead to tumor initiation and growth. Niches also
help stem cells maintain a balance between inactivation and activation.
In a review of the interactions between
stem cells and niches, Kateri A. Moore and Ihor R. Lemischka of Princeton University’s
department of molecular biology in New Jersey focus on the stem cell systems of
the intestinal epithelium, the epidermis and bone marrow. They note that several
themes have emerged during the study of these systems.
One is that anatomical organization
manages the spatiotemporal functions of stem cells, which is most apparent in the
stem cells in the intestines and in hair follicles. In addition, positive and negative
cellular signaling are integrated within the niches, and intercellular signaling
pathways are shared by the niche components.
According to the authors, among the
challenges for ongoing research efforts is the development of effective real-time
imaging techniques that can analyze stem cell behavior in vitro and niche behavior
in vivo. Other challenges include the development of equivalent definitions and
assay systems for all three stem cell systems, achieving a more complete understanding
of niche cell signaling pathways, the creation of in vitro systems that accurately
replicate the in vivo functions of niches, and the elucidation of how niche signals
are coupled with cell cycle regulation and other processes, and of how niches are
changed by stress or pathology.
The reviewers also briefly describe
the roles played by laser capture technology and by fluorescence microscopy
in stem and niche cell research. (Science, March 31, 2006, pp. 1880-1885.)
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